Core B is essential to support the microscopic imaging, quantitative analysis, and peripheral nerve injury model used in this PPG. The Core is used extensively by all three projects and contributes directly to multiple goals of these projects. The scope and resources of Core B have been significantly expanded by addition or update of new instrumentation (e.g. an AMT digital camera for the electron microscope, funded by an Administrative Supplement to the PPG) to meet the needs of the PPG projects. A significant addition is the provision of expertise and technical help to provide a single model of peripheral nerve injury in rodents that is used by all 3 projects. This eliminates variability between projects in surgical technique and microinjection of tracers in specific muscles or nerves, and facilitates direct comparison of data between projects to aid in interpretation. The Core facility is directed by a highly experienced investigator and research administrator, assisted by three highly trained and qualified research associates. The Core provides all necessary training to members of the PPG groups for authorized access and use of Core instruments and facilities; PPG members have priority access to the facility. Services include training and guidance for use of instruments and analytical techniques, assistance with design and/or interpretation of experiments, hands-on performance of tissue processing and imaging as required, electron microscopy processing and imaging, and microsurgery and tracer injection. Significant resources include 3 confocal microscopes (one is a multiphoton instrument with electrophysiology setup), electron microscope suite, Neurolucida system, fluorescence dissecting microscope, cryostats, vibratomes and ultramicrotomes, cryosubstitution system, a fully equipped histology laboratory, access to a state-of-the-art suite for microsurgery in rodents, and four off-line workstations for image processing and data analysis. Data is securely stored, and each PPG PI has secure access to a PPG shared data Cloud (1.0 terabyte) where they can access their own and each other's data and communicate seamlessly with the data acquisition instruments in the Core.